Anionic polymerization initiators for preparing macro-branched diene rubbers

ABSTRACT

Novel solid supported anionic polymerization initiators that are multiply metalated with Group IA alkali metal atoms are provided and employed to produce extremely high molecular weight branched diene polymers. The initiators are prepared by metalating a particle comprising a thermoplastic polymer or a cured elastomer in the presence of a polar coordinator. The polymers obtained by anionic polymerization employing the initiators are multiply branched, with a polymer chain covalently attached to the particle at virtually every metalation site. The macro-branched polymers exhibit desirable properties, such as an extremely high molecular weight, a controlled molecular weight distribution, T g  and vinyl content, and the ability to readily absorb hydrocarbon solvents and oils. The polymers are easily compounded to form vulcanizable elastomeric compounds and articles that have excellent resistance to wear and tear and exhibit reduced hysteresis properties.

BACKGROUND OF THE INVENTION

[0001] The invention relates to anionic polymerization resulting in veryhigh molecular weight, highly branched diene polymers. Moreparticularly, the invention relates to novel multiply-metalated, solidsupported anionic polymerization initiators that are useful forproducing such polymers. The macro-branched polymers synthesized by theprocess of the invention exhibit desirable properties, such as theability to absorb hydrocarbon solvents and oils, and are readilycompounded to form vulcanizable elastomeric compounds and articles thathave excellent resistance to wear and tear and exhibit reducedhysteresis properties.

[0002] When producing polymers for use in rubber articles, such astires, power belts, and the like, it is desirable that these polymersare easily processible during compounding and have a high molecularweight with a controlled molecular weight distribution, glass transitiontemperature (T_(g)) and vinyl content. It is also desirable thatreinforcing fillers, such as carbon black, be well dispersed throughoutthe rubber in order to improve various physical properties. Thisdispersion can be achieved, for example, by end capping polydienes byreacting a metal terminated polydiene with an end capping agent, or byutilizing functionalized anionic polymerization initiators such aslithium-based amine or amide initiators that incorporate a functionalgroup onto one or both ends of the polymer chain. Rubber articlesproduced from vulcanized elastomers exhibiting these properties, willhave reduced hysteresis resulting in an increase in rebound, a decreasein rolling resistance and less heat build-up when mechanical stressesare applied.

[0003] Anionic polymerization initiators based on lithium are well knownfor producing linear polydiene homopolymers and copolymers.Lithium-based macrocyclic anionic polymerization initiators have alsobeen described in U.S. Pat. Nos. 5,677,399 and 5,700,888. Theseinitiators are utilized to form stable macrocyclic polymers that havelow viscosities at high molecular weights and thus provide for enhancedpolymer processibility during molding, extruding and the forming offilms. Such polymers can be compounded to form vulcanizable elastomericcompounds and articles that exhibit reduced hysteresis properties.

[0004] There is still a need, however, for anionic polymerizationinitiators that can be used to synthesize high molecular weight linearpolymers that are easily processible and have the desirable propertiesdescribed above.

SUMMARY OF THE INVENTION

[0005] The present invention provides novel solid supported anionicpolymerization initiators that are multiply metalated and are useful forproducing extremely high molecular weight branched diene polymers. Inparticular, an advantage of the invention is that the macro-brancheddiene polymers are prepared using the invention initiators under normalconditions for an anionic polymerization process while the initiatorsare in suspension in a solution of monomers. Moreover, the initiators ofthe present invention are also suitable for use in gas phase anionicpolymerization of conjugated diene monomers, as disclosed in ourco-pending, co-assigned U.S. patent application Ser. No. ______, filedon the same day as this application (Attorney Docket No. 9704023),entitled “Gas Phase Anionic Polymerization of Diene Elastomers”, thedisclosure of which is hereby incorporated by reference. Because oftheir extremely high molecular weight and controlled molecular weightdistribution, T_(g) and vinyl content, the polymers produced by anionicpolymerization employing the invention initiators are useful forproducing many different high performance vulcanates. The macro-branchedpolymers synthesized by the process of the invention also exhibit otherdesirable properties, such as the ability to readily absorb hydrocarbonsolvents and oils, and they are easily compounded to form vulcanizableelastomeric compounds and articles that have excellent resistance towear and tear and exhibit reduced hysteresis properties.

[0006] In particular, the anionic polymerization initiators of theinvention have the formula P(Me)_(n), wherein P is a metalatableparticle having a diameter of about 1 micron to about 1000 micronscomprising a thermoplastic polymer or a cured elastomer. The particle ismultiply-metalated with a Group IA alkali metal (Me). The number ofmetal atoms covalently bound to the particle ranges from n=3 to n=amultiplicity of atoms, 10^(X) (e.g., 10¹⁰). The alkali metal atomsbonded to a single particle may all be the same or may be different fromeach other. The metal atoms may be any Group IA alkali metal includinglithium, sodium, potassium, rubidium, cesium and francium. Preferablythe metal atoms are selected from lithium, sodium and potassium and,more preferably, are a mixture of lithium atoms and at least one ofsodium atoms and potassium atoms. Most preferably, all of the alkalimetal atoms are the same and are lithium atoms.

[0007] As used in the context of the invention, the term “metalated”refers to an acid:base reaction, known to those skilled in the art,involving the transfer of a metal atom from a strong base to a moreacidic polymer with the concomitant transfer of a hydrogen atom from thepolymer to the base, thus forming a polymer carbon-metal covalent bond.A “metalatable” thermoplastic polymer or cured elastomer is one that canparticipate in this reaction and become metalated.

[0008] The above described anionic polymerization initiators are used tohomopolymerize conjugated diolefin monomers having from about 4 to about12 carbon atoms, and to copolymerize the conjugated diolefin monomerswith monovinyl aromatic monomers having from about 8 to about 20 carbonatoms, to prepare a macro-branched diene homopolymer or copolymer havingthe formula

P-[(polymer)-Me]_(n)

[0009] prior to quenching, wherein P, Me and n are the same aspreviously described and (polymer) represents a polymer chain covalentlybonded to the particle. The polymerization reaction is terminated with aterminating or a functionalizing agent. The resulting polymers have alow T_(g), preferably less than −20° C., more preferably less than −30°C., and most preferably less than −35° C., and are readily usable inrubber products such as tires.

[0010] The invention provides the initiators, the macro-branched dienepolymer, a vulcanizable elastomer composition formed from the polymer,and a tire having at least one component formed from the vulcanizableelastomer composition. The vulcanizable elastomer composition maycomprise the invention polymer only or may comprise a blend of theinvention polymer and at least one other polymer, such asstyrene-butadiene rubber, natural rubber, polyisoprene, poly-(ethylenepropylene diene monomer), and the like.

[0011] The invention further provides a method for preparing the anionicpolymerization initiators described above, comprising the step ofreacting (i) an alkali metal compound having the formula R(Me), where Rrepresents a hydrocarbyl group containing from one to about 20 carbonatoms, and Me is a Group IA alkali metal atom, with (ii) a particle asdefined above, in the presence of (iii) a polar coordinator, to form thereaction product having the formula P(Me)_(n), where P represents theparticle having covalently bonded alkali metal atoms and n is the sameas previously described. The molar ratio of the polar coordinator to thealkali metal compound is about 0.03:1 to about 4:1, preferably about0.05:1 to about 1:1, and more preferably about 0.06:1 to about 0.5:1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a schematic illustration of an invention initiatorcomprising a particle metalated with three alkali metal atoms.

[0013]FIG. 2 is a schematic illustration of the initiator of FIG. 1metalated with a multiplicity of surface-bound alkali metal atoms.

[0014]FIG. 3 is a schematic illustration of an invention initiatorcomprising the particle where the inner matrix of the particle ismultiply metalated.

[0015]FIG. 4 is a schematic illustration of an invention initiatorcomprising the particle where both the surface and the inner matrix ofthe particle are multiply metalated.

[0016]FIG. 5 is a schematic illustration of the macro-branched dienepolymer formed with the invention initiator.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The invention provides a novel solid supported anionicpolymerization initiator for anionic polymerization of conjugateddiolefin monomers having from about 4 to about 12 carbon atoms, andcopolymerization of the conjugated diolefin monomers together withmonovinyl aromatic monomers having from about 8 to about 20 carbonatoms, as described below, to form a macro-branched diene polymer. Theinitiator has the formula

P(Me)_(n)

[0018] where P is a metalatable particle having a diameter of about 1micron to about 1000 microns comprising a thermoplastic polymer or acured elastomer, Me is a Group IA alkali metal covalently bonded to theparticle, and n is an integer equal to or greater than 3. Morepreferably, n represents a multiplicity of alkali metal atoms (Me),10^(X) (e.g., 10¹⁰), and the particle comprises a multiplicity ofcovalently bonded alkali metal atoms.

[0019] The metal atoms may be any Group IA alkali metal includinglithium, sodium, potassium, rubidium, cesium and francium. Althoughrubidium, cesium and francium are usable in the invention initiator,their use is less preferred because they are comparatively expensive.Therefore, the metal atoms are preferably lithium, sodium or potassiumatoms, and more preferably are a mixture of lithium atoms and sodiumatoms and/or potassium atoms. Most preferably, all of the alkali metalatoms are lithium.

[0020] The alkali metal atoms on a single particle may all be the sameor may be different from each other, depending on the alkali metalcompound(s) used for the preparation of the initiator, as describedbelow. For example, the use of a single alkali metal compound, such asan alkyl lithium, an alkyl sodium, an alkyl potassium or another GroupIA alkyl metal compound produces particles metalated with a single typeof metal. However, the use of a mixture of an alkyl lithium compoundtogether with an alkyl sodium compound and/or an alkyl potassiumcompound and/or another Group IA alkyl metal compound as a co-agent formetalation produces particles metalated with lithium, as well as sodiumand/or potassium and/or the other metal. Preferably, an alkyl lithiumcompound alone is used in the preparation of the initiators, resultingin a particle metalated only with lithium.

[0021] Schematic illustrations of the invention initiator are presentedin FIGS. 1-4. In one embodiment of the invention illustrated in FIG. 1,the initiator 1 comprises a thermoplastic polymer particle or a curedelastomer particle 2 having carbon atoms to which three (n=3) alkalimetal atoms (Me) 3 are covalently bonded, each to a different carbonatom. In a preferred embodiment illustrated in FIG. 2, the particle 2has a multiplicity of alkali metal atoms 3 bonded to a multiplicity ofcarbon atoms on the particle. The particle 2 comprises an outer surface4 and an inner matrix 5. Thus, as illustrated in FIGS. 2-4, the alkalimetal atoms 3 may be covalently bonded to the outer surface 4 (FIG. 2),or to the inner matrix 5 (FIG. 3), or to both the outer surface 4 andthe inner matrix 5 (FIG. 4).

[0022] In one embodiment of the invention, the particle comprises ametalatable thermoplastic polymer. Suitable metalatable thermoplasticpolymers for use in the invention include, but are not limited to,polyethylene, polypropylene, polystyrenes, substituted polystyrenes, andthe like. Other such metalatable thermoplastic polymers are well knownto those skilled in the art. The thermoplastic polymer preferably has aT_(g) of 80° C. to about 300° C. Thus, when employed as the particleportion of the anionic polymerization initiator to produce themacro-branched polymers illustrated in FIG. 5, the particle remains aspart of the macro-branched polymer complex. When these macro-branchedpolymers are compounded, the processing temperatures are higher than theT_(g) of the thermoplastic polymer particle and allow the breakup of thethermoplastic particle into smaller particles that could, in the limit,contain only one polymer/elastomer chain attached to the particle, thusallowing for better processibility of the polymers.

[0023] In another embodiment of the invention, the particle comprises ametalatable cured elastomer. The cured elastomer may be any metalatablecured elastomer known to those skilled in the art, including compoundedcured rubber, such as scrap tire rubber. Exemplary cured elastomerssuitable for use in the invention are styrene butadiene rubber, naturalrubber, polybutadiene, polyisoprene, and the like. Other suchmetalatable cured elastomers are well known to those skilled in the art.Because some oils, curing agents and other ingredients in compoundedcured rubber may interfere with the metalation of the particle using analkali metal compound, the compounded cured rubber particle ispreferably extracted with acetone for at least 16 hours to substantiallyremove at least the curing agents, prior to use in preparation of theinitiator. When the macro-branched polymers that include the curedelastomeric particles described above are compounded or milled, thepoints of attachment of the polymers to the particles areshear-degraded, thus allowing for better processibility of the polymers.

[0024] The particles, having a diameter of about 1 to about 1000microns, may be conveniently sized by passing them through a mesh offixed pore size, as is well known in the art. For example, 20-meshparticles are about 841 microns or less in diameter; 200-mesh particlesare about 74 microns or less; and 400-mesh particles are about 37microns or less. The number of metalation sites on the particles dependson the size of the particles, the concentrations of the alkali metalcompound and the polar coordinator employed in the metalation reaction,the process times and temperatures, and the like.

[0025] To prepare the anionic polymerization initiator, the methodcomprises the step of reacting (i) an alkali metal compound having theformula R(Me), where R represents a hydrocarbyl group containing fromone to about 20 carbon atoms and Me is a Group IA alkali metal, with(ii) a particle as described above, in the presence of (iii) a polarcoordinator. The polar coordinator is an activator of the Group IAalkali metal atom and, as known to one skilled in the art, is requiredfor the formation of the carbon atom-metal atom covalent bond duringmetalation of the particle.

[0026] In general, the initiators according to the present invention canbe prepared, under anhydrous and anaerobic conditions, by forming asuspension of the thermoplastic polymer or cured elastomer particlesdescribed above in an anhydrous hydrocarbon solvent, such ascyclohexane, hexane, benzene, toluene, pentane, heptane, and the like,in a dry nitrogen atmosphere. To this suspension is then added a polarcoordinator, followed by the addition of an alkali metal compound,described below, in the same or a similar solvent. The molar ratio ofthe polar coordinator to the alkali metal compound ranges from about0.03:1 to about 4:1, preferably about 0.05:1 to about 1:1, and morepreferably about 0.06:1 to about 0.5:1. The optimum amount of particlespresent in the reaction mixture varies with the selected ratio of polarcoordinator to alkali metal compound, the type of particle employed, theparticle diameter, and the degree of metalation desired. One skilled inthe art will be able to select the proper amount of particles byexamining the exemplary data reported herein in Table 1. The variousreaction temperatures and times which may be employed to prepare theinitiators are known to one skilled in the art of anionic polymerizationinitiator preparation.

[0027] The alkali metal compound employed in the preparation of thesolid supported anionic initiators has the formula R(Me), where Me is ametal of Group IA of the Periodic Table of the Elements preferablyselected from lithium, sodium and potassium, and more preferably islithium, and R is a hydrocarbyl group having from one to about 20 carbonatoms. Although lithium alkali metal compounds are most preferred in themethod, sodium and/or potassium and/or other Group IA alkali metalcompounds may also be separately hemployed. Preferably, however, theseother compounds are used in a mixture with a lithium compound and thesodium and/or potassium and/or other Group IA compound acts as aco-agent with the lithium compound for metalation. Thus, as describedabove, the resulting particles may be metalated with one or more typesof alkali metal atoms derived from the alkali metal compound(s).

[0028] Typical R groups include aliphatic and cyclo-aliphatic groupssuch as alkyls, cycloalkyls, alkenyls, alkynyls, aryls and aralkyls.Specific examples of R groups include, but are not limited to, methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-amyl, isoamyl,n-hexyl, n-octyl, n-decyl, cyclopentyl-methyl, cyclohexyl-ethyl,cyclopentyl-ethyl, methyl-cyclopentylethyl, cyclopentyl, cyclohexyl,2,2,1-bicycloheptyl, methylcyclopentyl, dimethylcyclopentyl,ethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl,isopropylcyclohexyl, combinations of these, and the like. A preferablealkali metal compound for use in preparing the initiators of theinvention is n-butyl lithium.

[0029] Each metalated particle thus prepared is a solid supportedinitiator that is stable for at least a month or more and is useful foranionic polymerization of anionically-polymerizable monomers to yield amacro-branched polymeric product. Because of the polymeric nature of theparticles, each particle readily absorbs the hydrocarbon solvent and isthus is best described as a highly swollen particle. For example, eachgram of a 200-mesh scrap rubber particle may contain two to five gramsof a solvent in its inner matrix.

[0030] As described above, the swollen particle is metalated with atleast three or, preferably, a multiplicity of metal atoms, depending onthe selected reaction conditions. Metalation of the particle occurs inthe presence of a polar coordinator associated with the polymercarbon-metal bond. Such metalation reactions employing a polarcoordinator are known to those skilled in the art. The polar coordinatorremains associated with the carbon-metal bond of the initiatorthroughout the anionic polymerization process. However, the presence ofthe polar coordinator associated with the initiator results in amodification of diene polymerization that gives a reduced level of 1,4incorporation of monomers and a concomitant increase in the T_(g) of thepolymer produced (i.e., the higher the concentration of the polarcoordinator in the polymerization reaction mixture, the higher is theglass transition temperature (T_(g)) of the resulting diene polymer).The conventional procedure for preparing a standard (non-invention)metalated polymer from an alkali metal compound and a polar coordinatoremploys a molar ratio of the polar coordinator to the alkali metal ofabout 2:1. However, if a ratio of 2:1 were employed to multiply metalatethe invention initiators which are subsequently used to polymerizeconjugated diene monomers, the polymerization result would be a highT_(g) graft copolymer product (e.g., a very high vinyl polybutadienegrafted onto a low vinyl 1,4-polybutadiene). It is an object of thepresent invention to produce polymers having a low T_(g), preferablyless than −20° C., more preferably less than −30° C., and mostpreferably less than −35° C., for use in rubber products, such as tires.Therefore, it is desirable to prepare the present initiators in thepresence of a lower than standard molar ratio of polar coordinator toalkali metal compound. Surprisingly, it has been discovered herein thatnot only can the molar ratio of the polar coordinator to the alkalimetal compound be reduced to less than 2:1, but the degree of metalationof the particle is actually increased when the molar ratio of the polarcoordinator to the alkali metal compound is decreased to values as lowas about 0.03:1.

[0031] Compounds useful as polar coordinators are organic and include,but are not limited to, tetrahydrofuran, linear and cyclic oligomericoxolanyl alkanes such as 2-2′-di(tetrahydrofuryl) propane, dipiperidylethane, dimethyl ether, pentamethyl diethylenediamine,diazabicyclooctane, hexamethylphosphoramide, N-N′-dimethylpiperazine,diethyl ether, tributylamine and the like. The linear and cyclicoligomeric oxolanyl alkane polar coordinators are described in U.S. Pat.No. 4,429,091, the subject matter of which regarding polar solvents isincorporated herein by reference. Other compounds useful as polarcoordinators include those having an oxygen or nitrogen hetero-atom anda non-bonded pair of electrons. Examples include dialkyl ethers of monoand oligo alkylene glycols; “crown” ethers; fully alkylated diaminessuch as tetramethylethylene diamine (TMEDA); and fully alkylatedtriamines.

[0032] The initiators prepared according to the method of the inventionare employed with an anionically-polymerizable monomer to yieldmacro-branched diene polymers having the formula

P-[(polymer)-Me]_(n)

[0033] prior to quenching, where P, Me and n are the same as describedabove, and (polymer) represents a polymer chain covalently bonded to theparticle, wherein the polymer component of the polymer chain ispreferably selected from conjugated diolefin monomers having from about4 to about 12 carbon atoms, and copolymers and terpolymers of theconjugated diolefin monomers together with monovinyl aromatic monomershaving from about 8 to about 20 carbon atoms. Preferably, the monomersare selected from styrene, butadiene, isoprene, and mixtures of these.As described below, vulcanizable elastomer compositions are preparedfrom the macro-branched diene polymers by compounding the polymers withabout 5 to about 80 parts by weight of carbon black per 100 parts byweight of the polymer. Preferably, the vulcanizable elastomercomposition comprises a selection from the group consisting of styrenebutadiene rubber, polybutadiene rubber, polyisoprene rubber, isoprenebutadiene rubber, terpolymer rubbers of styrene, butadiene and isoprene,and mixtures of these rubbers.

[0034] A method of preparing a macro-branched diene polymer having theformula

P-[(polymer)-Me]_(n)

[0035] prior to quenching, comprises the step of polymerizing at leastone monomer selected from the group consisting of conjugated diolefinmonomers having from about 4 to about 12 carbon atoms and monovinylaromatic monomers having from about 8 to about 20 carbon atoms, in thepresence of an anionic polymerization initiator having the formulaP(Me)_(n), wherein P represents the particle metalated with n covalentlybonded alkali metal atoms, as described above.

[0036] Typically, the initiator is used to polymerize unsaturatedhydrocarbon monomers such as butadiene, isoprene and the like, andcopolymers thereof with monovinyl aromatics such as styrene and itsderivatives such as a-methyl styrene, p-methyl styrene and the like.Thus, the macro-branched elastomeric products include diene homopolymersfrom monomer A and copolymers thereof with monovinyl aromatic monomersB. Exemplary diene homopolymers are those prepared from conjugateddiolefin monomers having from 4 to about 12 carbon atoms. Exemplaryvinyl aromatic copolymers are those prepared from monomers having from 8to about 20 carbon atoms. Preferred macro-branched elastomers includediene homopolymers, such as polybutadiene and polyisoprene, copolymers,such as styrene butadiene rubber and isoprene butadiene rubber, andterpolymers consisting of styrene, butadiene and isoprene. Copolymersand terpolymers can comprise from about 99 to 10 percent by weight ofdiene units and from about 1 to about 90 percent by weight of monovinylaromatic units, totaling 100 percent. The polymers, copolymers andterpolymers of the present invention may have 1,2-microstructurecontents ranging from about 10 to about 80 percent, with the preferredpolymers, copolymers or terpolymers having 1,2-microstructure contentsof from about 25 to 65 percent, based upon the diene content.

[0037] The elastomeric copolymers are preferably random copolymers whichresult from simultaneous copolymerization of the monomers A and B withrandomizing agents, as is known in the art. Block copolymers, poly(b-styrene-b-butadiene-b-styrene) are thermoplastic elastomers,sometimes referred to as S-B-S polymers.

[0038] The initiators of the present invention form “living”macro-branched diene polymers from the foregoing monomers. FIG. 5 is aschematic representation of a macro-branched polymer 20 producedemploying the invention initiators. A polymer chain 12 can potentiallybe polymerized from each metalated site of the highly swollen particle10. However in practice, where there are a large multiplicity ofmetalated sites, it is likely some of the sites may be unavailablebecause they may be concealed or partially concealed by adjacent growingpolymer chains and the like. In this case, at least a majority of themetalated sites are available to produce polymer chains. The metal atom14 is carried on the living end of the polymer chain prior to quenching.As described above, each particle may comprise from three to amultiplicity of polymer chains. Moreover, polymer chains may be producedat metalated sites in the inner matrix of the particle, sincepolymerizable monomers are dissolved in solvent that can enter theparticle and are also soluble in both the particle and in the growingpolymer chains.

[0039] The polymer chains may be any of the foregoing dienehomopolymers, monovinyl aromatic homopolymers, diene/monovinyl aromaticrandom copolymers, block copolymers, or mixtures of any of theforegoing. Typically, about 0.5% to about 1% of the polymer product maycomprise the original particle used in the initiator. However, theconcentration of the particle in the product can be changed by varyingparameters such as the degree of metalation of the particles, e.g., bychanging the initiator preparation ingredient concentrations, theparticle sizes, and the like, or changing the concentration of monomersin the polymerization reactions, and the like.

[0040] Polymerization is usually conducted in a conventional hydrocarbonsolvent for anionic polymerizations, such as cyclohexane, hexane,benzene, toluene, pentane, heptane, and the like. Various techniques forsolution polymerizations, such as batch, semi-batch and continuouspolymerization may be employed. If a polar coordinator is optionallyadded to the polymerization ingredients, amounts range between about 0.1to about 90 or more equivalents per equivalent of the alkali metal. Theamount depends on the type of polar coordinator that is employed, theamount of vinyl desired, the level of styrene employed and thetemperature of the polymerizations, as well as the selected initiator.

[0041] According to the process of the invention, polymerization isbegun by charging a blend of the monomer(s) and solvent to a suitablereaction vessel, followed by the addition of the initiator. Theinitiator is typically in the form of a slurry (suspension) in ahydrocarbon solvent that can be syringed into the reaction vessel. Thedegree of metalation of the initiator particle is determined bytitration. As with the preparation of the initiator, the polymerizationreaction is carried out under anhydrous, anaerobic conditions. Often, itis conducted under a dry, inert gas atmosphere. The polymerization canbe carried out at any convenient temperature, such as about −30° C. toabout 200° C. For batch polymerizations, it is preferred to maintain thepeak temperature at from about 49° C. to about 149° C., and morepreferably from about 80 ° C. to about 120° C. Polymerization is allowedto continue under agitation for about 0.15 to 24 hours.

[0042] After polymerization is complete, the resulting polymer isquenched by a terminating agent that may be a protic quenching agentsuch as water, steam or an alcohol such as isopropanol, or afunctionalizing agent described below, to obtain a macro-branched dienepolymer. The terminating agent is added to the reaction vessel, and thevessel is agitated for about 0.1 to about 4.0 hours. Quenching isusually conducted by stirring the polymer and quenching agent for about0.25 hours to about 1.0 hour at temperatures of from about 30° C. toabout 120° C. to ensure a complete reaction.

[0043] Lastly, the solvent is removed from the polymer by conventionaltechniques. These include steam or alcohol coagulation, thermaldesolventization, or any other suitable method. Additionally, solventmay be removed by drum drying, extruder drying, vacuum drying or thelike. Desolventization by drum-drying, coagulation in alcohol, steam orhot water desolventization, extruder drying, vacuum drying, spraydrying, and combinations thereof are preferred. An antioxidant, such asbutylated hydroxy toluene (BHT) and/or an antiozonant compound isusually added to the polymer or polymer cement at or before this stage.

[0044] Functionalizing agents may be employed as terminating agents.These agents are compounds that provide a functional group that remainson the end of the polymer chain. Any compounds providing terminalfunctionality (e.g., “endcapping”) that are reactive with the polymerbound metal atom moiety can be selected to provide a desired functionalgroup. However, it is preferable that the functionalizing agents are notalso coupling agents (i.e., the functionalizing agents should not coupletogether the chain ends) so that the branched structure of the polymeris maintained. Functionalizing agents are particularly preferred whenelastomers are polymerized by the process of the invention because thefunctional group promotes uniform and homogeneous mixing with fillers,such as silica and carbon black. Therefore, for example, compounding ofvulcanizable macro-branched elastomers, prepared by the process of theinvention, results in rubber products exhibiting improved physicalproperties, such as reduced hysteresis, which means a rubber producthaving increased rebound, decreased rolling resistance in tires, andlessened heat build-up when subjected to mechanical stress. Examples ofsuch compounds are alcohols, substituted aldimines, substitutedketimines, Michler's ketone, 1,3-dimethyl-2-imidazolidinone, 1-alkylsubstituted pyrrolidinones, 1-aryl substituted pyrrolidinones, tributyltin chloride, and mixtures of these. Further examples of reactivecompounds include the terminators described in U.S. Pat. Nos. 5,066,729and 5,521,309, the subject matter of which, pertaining to terminatingagents and terminating reactions, is hereby incorporated by reference.The practice of the present invention is not limited solely to theseterminators, since other compounds that are reactive with the polymerbound alkali metal atom can be selected to provide a desired functionalgroup.

[0045] The preferred final polymerization product, the macro-brancheddiene polymer, resembles fish “caviar”. This product, which contains theinitiator particle, may then be compounded or milled to disperse thethermoplastic polymer particle or shear-degrade the cured elastomerparticle in the center of the polymer, as described above, and reducethe polymer to a base molecular weight.

[0046] Usually each of the polymer chains of the macro-branched polymerhave a molecular weight of about 20,000 to about 500,000, preferablyabout 100,000 to about 200,000, thus producing a macro-branched polymerhaving molecular weights that are several orders of magnitude higherthan known linear polymers as measured by conventional gel permeationchromatographic (GPC) techniques. Preferably, the polydispersity (theratio of the molecular weight to the number molecular weight) of thepolymers can be controlled over a wide range, from 1 to about 20,preferably 1 to about 5, and more preferably 1 to about 2.

[0047] A theoretical calculation of the molecular weights possible forthe macro-branched polymers is presented below. The calculation assumesa 200-mesh ground tire rubber particle and uses the initiator labeled #4illustrated in Table 1.

[0048] Assuming particles are uniformly shaped spheres with:

d=74 μm

r=37 μm Assuming uniform density of ground tire rubber as:$\rho = {1.16*10^{6}\frac{gm}{m^{3}}}$ Surface Area of Sphere:A = 4 * π * r² Volume of Sphere: $V = {\frac{4}{3}*\pi*r^{3}}$Mass of 1 particle: ${mass} = {{V*\rho} = {\frac{4}{3}*\pi*r^{3}*\rho}}$mass = 0.246  μ  gm Number particlees per gm ground  tire rubber:$\frac{\# \quad {particles}}{{gm}\quad {ground}\quad {tire}} = {\frac{1}{0.246\quad \mu \quad {gm}} = {4.065*10^{6}\frac{particles}{{gm}\quad {ground}\quad {tire}}}}$#of living sites per particles: $\begin{matrix}{\frac{\# \quad {living}\quad {sites}}{particle} = \quad {\frac{\left( {{``X"}\quad {mmol}\quad {Li}^{+}} \right)}{\left( {{gm}\quad {ground}\quad {tire}} \right)}*\frac{\left( {{gm}\quad {ground}\quad {tire}} \right)}{\left( {{``Y"}\quad \# \quad {particles}} \right)}*}} \\{\quad {\frac{\left( {6.022*10^{23}\quad {molecules}} \right)}{({mol})}*\frac{({mol})}{\left( {1000\quad {mmol}} \right)}}}\end{matrix}$

[0049] If 40 gm of monomers are polymerized using 10 cc of catalyst #4(0.33 molar), the expected molecular weight would be:

MW=approximately 26,000$\frac{\# \quad {MW}}{particle} = {1.6*10^{19}\frac{MW}{particle}}$

[0050] The highly branched polymers produced according to the inventionexhibit desirable properties in addition to their extremely highmolecular weight. For example, the polymers exhibit excellent oilabsorption properties and are easily compounded. They are also readilymixed with other polymers, such as styrene butadiene rubber, naturalrubber, polybutadiene, and the like, to form a polymer blend. Theinvention polymers also do not “cold flow” (i.e. a polymer “ball”retains its integrity as a ball over time, in contrast to a polymer thatdoes exhibit “cold flow” and would “puddle”).

[0051] The macro-branched polymers synthesized by the process of theinvention may also be compounded to form vulcanizable elastomericcompounds and articles that exhibit excellent resistance to wear andtear and reduced hysteresis properties. Articles, such as tires, shockabsorbers, mounts, power belts and the like, will show an increase inrebound, a decrease in rolling resistance and have less heat build-upwhen mechanical stresses are applied, resulting in improved fueleconomy. Decreased rolling resistance is, of course, a useful propertyfor pneumatic tires, both radial as well as bias ply types and thus, thevulcanizable elastomeric compositions of the present invention can beutilized to form treadstocks for such tires. The composition can also beused to form other elastomeric tire components such as subtreads, blacksidewalls, body ply skims, bead fillers and the like.

[0052] The polymers of the present invention can be utilized as 100parts of the rubber in the treadstock compound, or they can be blendedwith any conventionally employed treadstock rubber which includesnatural rubber, synthetic rubber and blends thereof. When the polymersof the present invention are blended with conventional rubbers, theamounts can vary widely with a lower limit comprising about 10 to 20percent by weight of the total rubber. The minimum amount will dependprimarily upon the degree of hysteresis reduction desired. Thus, thecompounds can contain 10 to 100% by weight of the inventive polymer,with the balance, if any, being a conventional rubber.

[0053] The polymers can be compounded with all forms of carbon black inamounts ranging from about 5 to 80 parts by weight, per 100 parts ofrubber (phr), with about 35 to 60 phr being preferred. The carbon blacksmay include any of the commonly available, commercially-produced carbonblacks. Examples of preferred carbon black compounds are described inU.S. Pat. No. 5,521,309, the subject matter of which, relating to carbonblack compounds, is incorporated by reference herein. Silica can be usedin place of all or part of the carbon black.

[0054] The reinforced rubber compounds can be cured in a conventionalmanner with known vulcanizing agents at about 0.1 to 10 phr. For ageneral disclosure of suitable vulcanizing agents, one can refer toKirk-Othmer, Encyclopedia of Chemical Technology, 3rd ed., WileyInterscience, N.Y. 1982, Vol. 20, pp. 365-468, particularly“Vulcanization Agents and Auxiliary Materials”, pp. 390-402. Vulcanizingagents can be used alone or in combination.

[0055] Vulcanizable elastomeric compositions of the invention can beprepared by compounding or mixing the macro-branched polymers herein,with carbon black and other conventional rubber additives including, forexample, fillers, such as silica, plasticizers, antioxidants, curingagents and the like, using standard rubber mixing equipment andprocedures. Such elastomeric compositions, when vulcanized usingconventional rubber vulcanization conditions, have reduced hysteresisproperties and are particularly adapted for use as tread rubbers fortires having reduced rolling resistance.

EXAMPLES AND GENERAL EXPERIMENTAL PROCEDURE Initiator Preparation

[0056] In order to demonstrate the preparation and properties of thesolid supported anionic initiators prepared according to the presentinvention, acetone-extracted ground cured rubber particles (i.e.,substantially curative free particles) or styrene butadiene rubberparticles or natural rubber particles were reacted with a lithiumhydrocarbyl compound in the presence of a polar coordinator to formmulti-lithiated particles. These initiators were then used to polymerizea solution of butadiene monomers. The described particles, alkyl metalcompound, polar coordinator, and solvents are intended to be onlyexamples of those that may be used in the process of the invention, andtheir particular use is not intended to be limiting, as other particles,alkali metal compounds, polar coordinators and solvents may be utilizedby those skilled in the art.

[0057] Initiator Preparation Procedure

Example 1

[0058] This example describes the preparation of a solid supportedinitiator employing 200 mesh ground scrap tire rubber (Rouse RubberIndustries) as the particles. Prior to use in preparing the initiator,the particles were extracted with acetone for at least 16 hours toremove substantially all curing agents. The initiator was prepared in a32-ounce beverage bottle that was dried by baking for at least 16 hoursat 115° C. and then capped with a crown, two-hole cap and rubber liner.The bottle was cooled while purging with dry nitrogen and labeled asinitiator #4. To the bottle was added 4.5 grams of the ground scraprubber particles. The bottle was then capped and 50 grams of hexane wasadded, followed by purging with nitrogen. Then 1.9 milliliters (ml) of6.62 molar (M) tetramethyl ethylene diamine (TMEDA) was added, followedby 100 grams of 3% by weight n-butyl lithium (BuLi) in hexane. Thebottle was heated in a 50° C. rotating bottle bath for 24 hours. Thebottle was then removed from the bottle bath and allowed to cool to roomtemperature.

[0059] To remove any free BuLi remaining, an initial hexane dilution wasadded (55 grams) and the bottle was allowed to sit still while theparticles in the bottle fell to the bottom. The top layer of solvent wasthen removed (96 grams), and a second dilution of hexane was added (113grams). The bottle was vigorously shaken and then allowed to sit whilethe particles again fell to the bottom. The second solvent extract wasthen removed from the bottle (109 grams). A third dilution was added(102 grams) of hexane, a third extraction was performed (206 grams) andthe particles were then re-suspended in 50 grams of hexane. Theresulting suspension contained 4.5 grams of lithiated ground scrap tirerubber in 59 grams of hexane. Analysis by butane evolution after alcoholtermination gave 89% of the BuLi as reacted, and thus the finalsuspension had a concentration of 0.33 M.

[0060] The solid supported initiator in suspension was then stored underpressure in a cool environment (refrigerator) to prevent decompositionof the initiator.

[0061] This procedure was used to prepare different solid supportedinitiators employing cured elastomers as the particles with thevariations in ingredients and ingredient concentrations as listed inTable 1. Some properties of the initiators are also included in Table 1.

[0062] As illustrated in Table 1, as the ratio of TMEDA to BuLidecreased from about 2:1 to about 0.25:1, and from thence to 0.135 and0.067, the millimoles of lithium covalently bonded per gram of rubber,the molar concentration of particle lithium, and the percentage of BuLithat reacted increased significantly. The percentage of free BuLi in theinitiator solution is a function of the degree of washing with solventafter the initiator is formed.

Example 2

[0063] This example describes the preparation of an initiator using athermoplastic polymer as the particle. The polymer employed is acopolymer of modified styrenes having a molecular weight of 2,900 andT_(g) of 100° C., with the brand name ENDEX® 155 (Hercules Inc.,Wilmington, Del.). The initiator was prepared in a 32-ounce beveragebottle that was dried by baking for at least 16 hours at 115° C. andthen capped with a crown, two-hole cap and rubber liner. The bottle wascooled while purging with dry nitrogen. To the bottle was added 5 gramsof ENDEX®. Fifteen to 20 dry marbles were added to the bottle. Thebottle was then capped and 35 ml of hexane was added, followed bypurging with nitrogen. Then 1.2 ml of 6.62M TMEDA was added, followed by15 ml of a 1.6M solution of BuLi in hexane. The bottle was heated in a50° C. rotating bottle bath for 24 hours. The bottle was then removedfrom the bottle bath, allowed to cool to room temperature, and excessliquid was removed. The bottle was vigorously shaken on a mechanicalshaker to smash large particles into small ones. The particles were thenre-suspended in 50 grams of hexane. The solid supported initiator insuspension was then stored under pressure in a cool environment(refrigerator) to prevent decomposition of the initiator.

Polymer Preparation

[0064] The following examples illustrate the process of the inventionfor the preparation of macro-branched diene polymers using the inventioninitiators. However, the examples are not intended to be limiting, asother methods for preparing these macro-branched diene polymers from theinvention initiators may be determined by those skilled in the art.

[0065] The polymer was prepared in a 32-ounce beverage bottle that wasdried by baking for at least 16 hours at 115° C. and then cooled whilepurging with dry nitrogen. The bottle was then capped with a crown,two-hole cap and rubber liner, pressure checked and again nitrogenpurged. The bottle was labeled as polymer #P-18 and then placed in abottle guard. To the bottle was added 50 grams of hexane, followed by150 grams of 33% by weight butadiene in hexane. Finally, 5 ml ofinvention initiator #4, prepared as in Example 1, was added. The bottlewas inserted into a 50° C. rotating bottle bath for 24 hours. The bottlewas then removed from the bottle bath and 2.0 ml of isopropanol (neat)was added to terminate the polymer. The bottle was then allowed to coolto room temperature. The contents in the bottle appeared more as a“solid” than a “liquid”, and appeared very similar to a fish “caviar”.The hexanes in the bottle were swollen in the polymer that was produced.

[0066] The bottle was vented, then cut open and the polymer was isolatedby removing the solvent on a drum dryer. The resulting processed productsheeted on the rolls of the drum dryer and was easily gathered.

[0067] Analysis of the polymer showed a 100% conversion of monomer togive a Mooney viscosity at 100° C. of 108.8. The polymer was 23.6%soluble in toluene and analysis of the soluble polymers by GPC gave anumber molecular weight (Mn) of 130,200 grams per mole and apolydispersity of 3.56. The T_(g) was −57.0° C., measured at midpoint.This T_(g) corresponds to a microstructure of 57% vinyl polybutadiene.

Characterization of the Polymers

[0068] The data of Table 2 illustrate properties of polymers similarlyprepared employing the initiators described in Table 1. Some of thepolymers are copolymers of butadiene and styrene, prepared by standardpolymerization procedures known to those skilled in the art.

[0069] The appearance of the some of the polymers was “caviar”,indicating that there was little free butadiene homopolymer producedand, therefore, there was little free BuLi remaining in the initiatorpreparation that was employed. Other preferred polymers appeared as a“caviar sludge”, indicating a small amount of homopolymerized butadiene.Other polymers appeared as a “slurry” or an “oily sludge”. Some of thepolymerization reactions resulted in a low conversion of monomer topolymer (“Low Conv”). Other polymerization reactions resulted in anundesirably high degree of homopolymerization of the monomers inaddition to production of macro-branched polymers (“High homo pzn”).

[0070] The preferred polymers were macro-branched, having high numbermolecular weights (Mn) ranging from 72,000 to 594,000, Mooneyviscosities at 100° C. ranging from 35 to 135, with a lowpolydispersity, a low 1,2-microstructure, and a T_(g) between −35° C.and −75° C., preferably about −35° C. to −55° C. As expected, polymerscontaining styrene showed a higher T_(g) than those without styrene.However, all of the prepared polymers listed in Table 2 had anacceptable T_(g) of less than −20° C. Preferred polymers also had a highpercentage of conversion of monomers and a low percentage of “soluble”polymer (i.e., free homopolymer). Exemplary preferred polymers shown inTable 2 are #P-10 made with initiator #3; #P-18, #P-19, #P-20 and #P-25all made with initiator #4; #P-35 made with initiator #7; #P-37 madewith initiator #8; #P-53 made with initiator #9; #P-54 and #P-55 madewith initiator #10, and #P-62 and #P-63 made with initiator #11.

[0071] While the invention has been described herein with reference tothe preferred embodiments, it is to be understood that it is notintended to limit the invention to the specific forms disclosed. On thecontrary, it is intended to cover all modifications and alternativeforms falling within the spirit and scope of the invention. TABLE 1CHARACTERIZATION OF INITIATOR #1 Total Lithium % Total % Molar BuLi InFree Part. BuLi TMEDA: Reac- BuLi Li/particle Conc. Res- Initiator BuLiin Initiator Part. Mesh Wt. gm BuLi TMEDA BuLi tants Reac- in slurryParticle idue Solution Initiator # Type Size (gm) (%) (mmol) (mmol)Ratio (cc) ted (mmol/g) Lithium (M) (M) Solution 1 Scrap 200 2.0 100 (3)46.9 99.30 2.118 2 Scrap 200 4.0 100 (3) 46.9 99.30 2.118 3 Scrap 2004.5 100 (3) 46.9 25.16 0.537  92 13 1.4 0.067 0.0071 0.074 9.6 4 Scrap200 4.5 100 (3) 46.9 12.58 0.268  89 27 2.8 0.142 0.0043 0.146 3.0 5Scrap 200 4.0  21 (15) 49.2 12.58 0.256 134 89 11.0  0.328 0.0002 0.3290.1 6 Scrap 200 4.0  21 (15) 49.2  6.62 0.135 147 83 10.2  0.279 0.00080.279 0.3 7 Scrap 200 4.0  21 (15) 49.2  3.31 0.067 143 77 9.5 0.2650.0008 0.266 0.3 8 Scrap 200 4.0  10 (15) 23.4 12.58 0.537 108 94 5.50.206 0.0000 0.206 0.0 9 SBR**  32 4.0 100 (3) 46.9 99.30 2.118 197 192.2 0.046 0.0206 0.066 31.1 10  SBR  32 4.0 100 (3) 46.9 99.30 2.118 24816 1.8 0.029 0.0204 0.050 41.1 11  NR***  18 4.0 100 (3) 46.9 99.302.118 186 19 2.2 0.048 0.0184 0.067 27.6 12  NR  18 4.0 100 (3) 46.999.30 2.118 214 21 2.5 0.046 0.0117 0.058 20.2

[0072] TABLE 2 CHARACTERIZATION OF FINAL POLYMERS Stock Amt. % 1,2 Bd* %% Polymer Initiator Age Used T_(g)(° C.) % (calc.from Monomer SoubleExtract Poly # # (Days) (cc) ML4 midpoint Styrene Tg) Converted PolymerMn disp. Notes P-1 1 1 10 128.5 −33 0 76.8 NA 11.4  93600 2.94 P-2 1 110 88.5 −29 0 79.8 NA 32.2 151000 2.94 P-3 2 1 5 88.3 −34 0 76.1 NA 7.4 96900 7.28 P-4 2 1 10 159.0 −32 0 77.6 NA 33.9 125100 1.84 P-5 2 1 1089.1 −29 0 79.8 NA 16.9 237000 1.75 P-6 2 9 10 89.6 −32 0 77.6 100.016.0 255300 1.99 P-7 2 9 10 104.2 −30 10 76.7 86.1 17.3 193000 2.74 P-82 9 10 134.6 −24 20 76.9 85.5 21.0 100300 4.51 P-9 2 9 10 133.4 −22 2574.9 93.6 19.0 158700 2.71 P-10 3 7 5 79.0 −39 0 72.1 85.0 22.6 2204002.86 P-11 3 7 5 109.9 −30 17 72.8 45.0 14.0 101500 6.27 P-12 3 7 5 110.7−28 22 70.9 46.0 12.8 101400 7.01 P-13 3 7 5 112.8 −22 25 74.9 90.0 21.1203700 2.95 P-14 3 24 10 125.4 −41.0 0 70.5 87.5 81.8 156000 1.80 SlurryP-15 3 24 10 129.8 −40.5 0 71.0 90.0 64.6 162000 1.80 Slurry P-16 3 2810 124.5 −41.5 0 70.0 87.0 51.5 167500 1.79 P-17 3 28 10 125.7 −57.0 056.7 87.0 65.3 156200 1.80 P-18 4 7 5 108.8 −57 0 56.7 100.0 23.6 1302003.56 P-19 4 7 5 89.0 −38 14 66.7 100.0 15.1 236000 3.23 P-20 4 7 5 90.7−33 23 64.2 100.0 23.7 370700 2.25 P-21 4 7 5 114.1 −29 31 58.1 78.015.1 222500 2.85 P-22 4 24 10 141.2 −56.5 0 57.1 87.5 85.4 112400 2.18Slurry P-23 4 24 10 130.8 −59.0 0 54.8 60.0 98.4 175300 1.86 Slurry P-244 28 10 132.3 −57.0 0 56.7 78.0 85.8 192900 1.75 P-25 4 28 10 142.1−29.5 33 53.7 89.0 78.1 206900 2.27 P-26 5 1 10 42.1 −62.5 0 51.4 79.895.8 111700 1.82 P-27 5 1 10 50.3 −46.0 20 52.0 85.0 97.6 102400 2.17P-28 5 2 10 120.4 −47.0 17 54.2 85.8 92.2 151900 2.55 Caviar sludge P-296 1 10 Too Low −76.0 0 37.0 88.0 99.4  72400 1.35 P-30 6 1 10 Too Low−55.0 20 39.8 92.0 100.0  60800 1.61 P-31 6 2 10 Too Low −57.0 17 41.689.2 99.5  75900 1.75 Oily sludge P-32 7 1 10 Too Low −79.0 0 33.4 84.098.3  72000 1.58 P-33 7 1 10 46.4 −66.5 20 21.6 80.0 99.4 116300 1.48P-34 7 2 10 125.7 −65.0 17 30.1 90.0 99.8 107000 1.60 High homo pzn*P-35 7 25 5 82.1 −34.5 25 59.0 90.6 543600 Caviar P-36 8 1 10 125.7−38.5 20 61.0 88.0 61.4 208000 2.66 P-37 8 2 10 94 −34.5 16 68.9 90.04.2 594000 2.37 Caviar P-38 8 2 10 107.8 −53.5 0 59.8 93.8 56.0 2482001.86 Caviar Sludge P-39 8 2 10 156 −35.5 18 66.2 93.5 34.5 185200 2.35Caviar Sludge P-40 8 2 20 144.5 −45.5 0 66.8 88.0 71.7 189700 1.78Caviar Sludge P-41 8 25 10 −85.0 0 25.5 86.4 300200 1.38 High homo pzn*P-42 8 25 10 −75.0 5 33.3 97.0 457300 1.97 High homo pzn* P-43 8 25 10−79.0 5 30 85.6 313700 1.48 High homo pzn* P-44 8 25 10 −73.5 8 29 80.3219800 1.41 High homo pzn* P-45 8 25 10 −73.5 10 25 78.8 239200 1.44High homo pzn* P-46 8 25 10 −71.5 11 25 80.3 211600 1.41 High homo pzn*P-47 9 1 10 132.9 −35 0 79.1 95.0 70.8 194800 1.59 P-48 9 6 5 106.8 −370 77.6 91.3 46.4 298600 1.89 P-49 9 6 5 121.0 −34 4.2 79.0 88.0 59.8226900 1.68 P-50 9 6 5 111.7 −32 8.3 79.9 85.0 40.1 268100 1.65 P-51 9 65 112.4 −26 16.7 81.9 92.0 18.2 408600 1.79 P-52 9 6 5 129.3 −36 20.868.4 47.5 26.3 490000 2.10 Low Sty Conv.** P-53 9 20 10 108.3 −37.0 073.8 89.0 23.6 210500 2.24 P-54 10 3 10 NA −36 0 74.5 23.0 11.5 3855003.04 P-55 10 10 2 106.7 −40 0 75.2 98.3 10.6 308500 1.78 Caviar LookingP-56 10 10 4 127.5 −35 0 79.1 86.0 85.2 146700 1.62 Slurry P-57 10 10 8126.5 −34 0 76.1 82.0 79.3 166400 1.63 Slurry P-58 10 10 16 122.5 −34 076.1 90.0 43.8 205300 1.54 Slurry P-59 10 17 10 NA −35.5 0 74.7 13.019.6 172500 6.55 Low Conv P-60 11 1 10 109.1 −35 0 79.1 90.0 13.5 2139002.10 P-61 11 20 10 122.1 −36.0 0 74.5 86.0 10.6 173800 2.17 P-62 11 2010 106.2 −30.5 10 76.1 89.0 14.0 399600 1.80 P-63 11 20 10 105.5 −24.020 76.9 88.0 18.2 374300 2.29 P-64 12 3 10 129.9 −36 0 74.5 89.5 47.1175000 1.54 P-65 12 10 4 NA −39 0 72.1 15.0 17.8 401000 2.46 Low ConvP-66 12 10 8 123.0 −38 0 76.8 90.8 70.4 173000 1.65 Slurry P-67 12 10 1697.5 −35 0 79.1 92.3 81.7 125000 1.65 Slurry P-68 12 17 10 96.0 −36.5 074.1 88.0 15.1 164600 3.63

We claim:
 1. An anionic polymerization initiator having the formulaP(Me)n wherein P is a metalatable particle having a diameter of about 1micron to about 1000 microns comprising a thermoplastic polymer or acured elastomer, Me is a Group IA alkali metal atom covalently bonded tothe particle, and n is an integer equal to or greater than
 3. 2. Theinitiator of claim 1 , wherein the thermoplastic polymer has a T_(g) of80° C. to about 300° C.
 3. The initiator of claim 1 , wherein the curedelastomer is a compounded cured elastomer that is substantially curativefree.
 4. The initiator of claim 1 , wherein the alkali metal atoms arelithium or sodium or potassium atoms.
 5. The initiator of claim 4 ,wherein the alkali metal atoms are lithium atoms.
 6. The initiator ofclaim 1 , wherein the alkali metal atoms are a mixture of lithium atomsand a selection from atoms of at least one of sodium, potassium,rubidium, cesium and francium.
 7. The initiator of claim 1 , wherein nis an integer representing a multiplicity of alkali metal atomscovalently bonded to the particle.
 8. The initiator of claim 7 , whereinthe molar concentration of metal atoms per gram of particles is fromabout 0.1 millimoles per gram to about 100 millimoles per gram.
 9. Theinitiator of claim 7 , wherein the particle comprises an outer surfaceand an inner matrix, and the alkali metal atoms are covalently bonded tothe outer surface or to the inner matrix or to both the outer surfaceand the inner matrix.
 10. A macro-branched diene polymer having theformula P-[(polymer)-Me]_(n) prior to quenching, wherein P represents aparticle having a diameter of about 1 micron to about 1000 micronscomprising a thermoplastic polymer or a cured elastomer, Me is a GroupIA alkali metal atom, n is an integer equal to or greater than 3, and(polymer) represents a polymer chain covalently bonded to the particle.11. The polymer of claim 10 , wherein the thermoplastic polymer has aT_(g) of 80° C. to about 300° C.
 12. The polymer of claim 10 , whereinthe cured elastomer is a compounded cured elastomer that issubstantially curative free.
 13. The polymer of claim 10 , wherein thealkali metal atoms are lithium or sodium or potassium atoms.
 14. Thepolymer of claim 13 , wherein the alkali metal atoms are lithium atoms.15. The polymer of claim 10 , wherein the alkali metal atoms are amixture of lithium atoms and a selection from atoms of at least one ofsodium, potassium, rubidium, cesium and francium.
 16. The polymer ofclaim 10 , wherein the polymer component of the polymer chain isselected from conjugated diolefin monomers having from about 4 to about12 carbon atoms, and copolymers and terpolymers of the conjugateddiolefin monomers together with monovinyl aromatic monomers having fromabout 8 to about 20 carbon atoms.
 17. The polymer of claim 16 , whereinthe monomers are selected from butadiene, styrene and its derivatives,and isoprene.
 18. The polymer of claim 10 , wherein n is an integerrepresenting a multiplicity of polymer chains covalently bonded to theparticle.
 19. The polymer of claim 10 , wherein each of the n polymerchains bonded to the particle has a molecular weight of about 20,000 toabout 500,000.
 20. The polymer of claim 10 , wherein the polymer has aglass transition temperature of less than −20° C.
 21. The polymer ofclaim 20 , wherein the glass transition temperature is less than −30° C.22. The polymer of claim 21 , wherein the glass transition temperatureis less than −35° C.
 23. A vulcanizable elastomer composition formedfrom the polymer of claim 10 and from about 5 to about 80 parts byweight of carbon black per 100 parts by weight of the polymer.
 24. Avulcanizable elastomer composition formed from the polymer of claim 20and from about 5 to about 80 parts by weight of carbon black per 100parts by weight of the polymer.
 25. A tire having at least one componentformed from the vulcanizable elastomer composition of claim 23 .
 26. Atire having at least one component formed from the vulcanizableelastomer composition of claim 24 .
 27. A method of preparing an anionicpolymerization initiator, comprising the step of: reacting (i) an alkalimetal compound having the formula R(Me), where R represents ahydrocarbyl group containing from one to about 20 carbon atoms, and Meis a Group IA alkali metal, with (ii) a metalatable particle having adiameter of about 1 micron to about 1000 microns comprising athermoplastic polymer or a cured rubber, in the presence of (iii) apolar coordinator, to form a reaction product having the formulaP(Me)_(n) wherein P represents the particle having covalently bondedalkali metal atoms, and n is an integer equal to or greater than
 3. 28.The method of claim 27 , wherein the alkali metal is lithium or sodiumor potassium.
 29. The method of claim 28 , wherein the alkali metal islithium.
 30. The method of claim 27 , wherein the alkali metal compoundrepresents a mixture of a lithium compound and a selection from at leastone of a sodium compound, a potassium compound, a rubidium compound, acesium compound and a francium compound.
 31. The method of claim 27 ,wherein the R group is selected from aliphatic and cyclo-aliphaticgroups consisting essentially of alkyls, cycloalkyls, alkenyls,alkynyls, aryls, aralkyls, and combinations thereof.
 32. The method ofclaim 27 , wherein the alkali metal compound is n-butyl lithium.
 33. Themethod of claim 27 , wherein the polar coordinator is selected from thegroup consisting essentially of tetrahydrofuran, linear oligomericoxolanyl alkanes, cyclic oligomeric oxolanyl alkanes, dialkyl ethers ofmono and oligo alkylene glycols, crown ethers, fully alkylated diamines,fully alkylated triamines, and mixtures thereof.
 34. The method of claim27 , wherein the molar ratio of the polar coordinator to the alkalimetal compound is about 0.03:1 to about 4:1.
 35. The method of claim 34, wherein the molar ratio is about 0.05:1 to about 1:1.
 36. The methodof claim 35 , wherein the molar ratio is about 0.06:1 to about 0.5:1 37.A method of preparing a macro-branched diene polymer having the formulaP-[(polymer)-Me]_(n), wherein P represents a metalatable particle havinga diameter of about 1 micron to about 1000 microns comprising athermoplastic polymer or a cured elastomer, Me is a Group IA alkalimetal, n is an integer equal to or greater than 3, and (polymer)represents a polymer chain covalently bonded to the particle, the methodcomprising the step of anionically polymerizing at least one monomerselected from the group consisting of conjugated diolefin monomershaving from about 4 to about 12 carbon atoms and the diolefin monomerstogether with monovinyl aromatic monomers having from about 8 to about20 carbon atoms, in the presence of an anionic polymerization initiatorhaving the formula P(Me)_(n), wherein P represents the particlemetalated with n covalently bonded alkali metal atoms.
 38. The method ofclaim 37 , wherein the monomer is dissolved in and the initiator issuspended in an anhydrous hydrocarbon solvent.
 39. The method of claim37 , further comprising the step of terminating the polymerization witha terminating agent or a functionalizing agent.
 40. The method of claim37 , wherein the terminating agent or the functionalizing agent isselected from the group consisting of alcohols, substituted aldimines,substituted ketimines, Michler's ketone, 1,3-dimethyl-2-imidazolidinone,1-alkyl substituted pyrrolidinones, 1-aryl substituted pyrrolidinones,tributyl tin chloride, and mixtures thereof.